Study On Synthesis And Properties Of Waterborne Polyurethane For Hot Melt Adhesive

Currently most polyurethane hot melt adhesive is solid on the market, with the faults of a high softening point, melt viscosity and construction technology. Waterborne polyurethane for hot melt adhesive can achieve coating process at room temperature using the simple and convenient equipments and it had a good performance in market. In this thesis, carboxylic / sulfonate aqueous polyurethane hot melt adhesive with solid content up to 50% have been synthesized. Effect of R value, the content of hydrophilic chain extender, AAS/DMPA mass ratio, the content of BDO, PBA3000/PBA2000 mole ratio and HDI/IPDI mole ratio on properties of waterborne polyurethane was deeply investigated. In addition, the article finally used the water-based acrylic resin to modification, in order to reduce the softening point of water-borne polyurethane.FT-IR curves confirmed the sulfonic groups and carboxylic groups were successfully inserted on the molecule chain. The results showed that the emulsion and Of WPU for hot melt adhesive with optimal properties could be obtained when the –NCO/-OH ratio is 1.2, the content of the hydrophilic chain extender is 2.0%, the AAS/DMPA mass ratio is 1:1, the content of BDO is 1.2%, the PBA3000/PBA2000 mole ratio is 3:1,and HDI/IPDI mole ratio is 1:1. TEM, GPC, DCS and TGA were used to investigate the waterborne polyurethane adhesive for hot melt adhesive, the results showed it had a good performance in stability, heat-resisting, mechanical and adhesive performance.Water-based acrylic resin had been used for physical modification in WPU for hot melt adhesive. The results showed that the emulsion and Of WPU for hot melt adhesive with optimal properties could be obtained when the acrylic acid molecular weight is 1.6 x 104, adding ratio is 30%, and the quality of the glass transition temperature is-30 ℃. WPU for hot melt adhesive have a good performance in strength, water resistance, storage stability and the softening point, and which of these several performance has reached the requirement of industry.